/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.extensions.sql.impl.schema;



import com.bff.gaia.unified.sdk.schemas.transforms.Convert;

import com.bff.gaia.unified.sdk.values.PBegin;

import com.bff.gaia.unified.sdk.values.PCollection;

import com.bff.gaia.unified.sdk.values.POutput;

import com.bff.gaia.unified.sdk.values.Row;



/**

 * {@code UnifiedPCollectionTable} converts a {@code PCollection<Row>} as a virtual table, then a

 * downstream query can query directly.

 */

public class UnifiedPCollectionTable<InputT> extends BaseUnifiedTable {

  private transient PCollection<InputT> upstream;



  public UnifiedPCollectionTable(PCollection<InputT> upstream) {

    super(upstream.getSchema());

    if (!upstream.hasSchema()) {

      throw new RuntimeException("SQL can only run over PCollections that have schemas.");

    }

    this.upstream = upstream;

  }



  @Override

  public PCollection.IsBounded isBounded() {

    return upstream.isBounded();

  }



  @Override

  public PCollection<Row> buildIOReader(PBegin begin) {

    assert begin.getPipeline() == upstream.getPipeline();

    return upstream.apply(Convert.toRows());

  }



  @Override

  public POutput buildIOWriter(PCollection<Row> input) {

    throw new IllegalArgumentException("cannot use [UnifiedPCollectionTable] as target");

  }

}